This invention relates generally to systems and methods for determining proper combinations or mixtures.
In many situations, it is necessary or desirable to combine or mix several substances or sources (e.g. of color or light), for instance, in order to obtain a desired color. Other properties may also need to be controlled or maintained within a desired range. Examples involving sources of color include the manufacture of fluorescent lamps for active matrix liquid crystal displays (AMLCD) for avionics applications, and tuning/specification of backlight color for various display applications such as light emitting diode (LED), organic light emitting diode (OLED), and cathode ray tubes (CRTs). Specifically, manufacture of fluorescent lamps for AMLCD avionics applications, as an example, may require tight control of lamp color within a desired range in order to maintain control of the optical output specifications. Color ranges or tolerances as low as plus or minus 0.005 in uxe2x80x2 vxe2x80x2 chroma or chromaticity coordinates (unitless parameters) for such applications are not uncommon. Fluorescent lamps typically require three phosphors (red/green/blue) blended together to coat the inside of the glass tube to meet the required color target. This blended slurry or mix of phosphors is typically excited through plasma in order to produce a white output. In the past, in the lamp industry, this blending or obtaining a desired mixture has generally been done empirically and required an experienced person with knowledge of both optics and phosphors. It typically took several iterations to meet the tight color tolerances or desired ranges of an avionics application.
It is one object and feature of the present invention to provide a system and method for determining the proper mixture of substances or sources, for instance, to obtain a desired color or chromaticity. Other objects and features of the present invention are that it be highly accurate and precise, that it be easy to use, and that it require only readily available hardware and software. In addition, it is an object of the present invention that some embodiments be suitable to allow a lamp manufacturer with little or no knowledge of optics to quickly and easily select quantities of phosphors for the manufacture of fluorescent lamps for AMLCD avionics applications.
In at least partial fulfillment of these objects, the present invention provides a system and method to accomplish, as an example, high-accuracy color mixing or combining sources of color. Specifically, the present invention provides a method for determining the proper mixture of substances or combination of sources (e.g. of light), for instance, to obtain a desired color. The method may comprise some or all of the steps of determining the desired chromaticity, determining the desired quantity of substances (e.g. phosphor mix) or light sources to be produced or used, calculating the proportion of each substance or source of light, and calculating the quantity of each substance or source of light that is required to meet the desired chromaticity and quantity of substance or source of light. The method may also comprise some or all of the steps of mixing the substances (e.g. mixing phosphors to produce a phosphor mix), preparing a prototype (either with the mix of substances or with the sources of light), measuring the chromaticity of the prototype, and determining if the chromaticity of the prototype is within the desired or required range. If the chromaticity is not within the desired or required range, the method typically further comprises the step of calculating any required adjustments in the quantities of substances (e.g. phosphors), light, or light sources. If the chromaticity is not within the desired or required range, the method may also further comprise the steps of mixing or adding the required adjustments of substances or light sources, preparing another prototype, and measuring the chromaticity of the prototype. This process may be repeated until the desired or required chromaticity is achieved. Once the chromaticity is within the desired or required range, the method may comprise the step of using the mix of substances or light sources to manufacture products. Other properties besides chromaticity, may need to be held within a desired range by controlling their proportion in a combination or mixture.
In specific embodiments, the present invention provides a method of obtaining a desired mixture of substances. The substances are generally mixed in a (e.g., predetermined) proportion, and the desired mixture will typically have at least one property that is influenced by the proportion of the substances in the desired mixture. The desired mixture may have a desired range for the property. The method may comprise the steps of: mixing the substances to form a working mixture; preparing a prototype with the working mixture; measuring the property of the prototype; comparing the property of the prototype with the desired range; calculating an adjustment in the proportion of the substances; and repeating these steps until the property of the prototype is within the desired range. The calculating step may involve using a computer, and a spreadsheet program may be used. The calculating may involve dividing the property into component bands and performing calculations, which may be iterative calculations, on each band.
The present invention also provides a method for determining a proper combination for obtaining a color within a desired range. This embodiment typically includes the steps of: calculating quantities of sources of color; combining the sources of color; preparing a prototype; measuring the chromaticity of the prototype; determining if the chromaticity of the prototype is within the desired range; and repeating these steps until the chromaticity of the prototype is within the desired range. The prototype may have three sources of color.
The present invention also provides, a computer implemented method for determining a proper mixture of phosphors for manufacturing florescent lamps that produce a chromaticity within a desired range. This embodiment typically includes the steps of calculating the proportion of each phosphor to obtain the desired chromaticity; mixing the phosphors to form a first working mixture; and preparing a first prototype using the first working mixture. It typically also includes measuring the chromaticity of the first prototype; and calculating a first adjustment in phosphor quantities. This embodiment generally also includes the steps of adding the first adjustment in phosphor quantities to the first working mixture to form a second working mixture; preparing a second prototype using the second working mixture; and measuring the chromaticity of the second prototype. The calculations may utilize hard coded values specifically determined for the phosphors being used, and may involve tristimulus values. The computer may further be used to calculate additional adjustments in phosphor quantities and additional prototypes may be made and measured.
The present invention also provides, in an exemplary embodiment, a computer program, specifically a spreadsheet, specifically a spreadsheet prepared for MICROSOFT EXCEL, which can accurately and easily be used to perform the step of calculating any required adjustments in the quantities of substances (e.g. phosphors) or light sources. The spreadsheet provided is specifically configured, as an example, to calculate adjustments in phosphor quantities required for manufacturing lamps for backlighting in avionics applications, specifically fluorescent lamps for AMLCD avionics applications. Use of the spreadsheet described includes the steps of inputting the measured chromaticity, the desired chromaticity, and starting phosphor weights for a prototype, pressing xe2x80x9cNormalizexe2x80x9d and xe2x80x9cCalculate Adjustmentxe2x80x9d buttons, and reading the recommended adjustment. The spreadsheet performs various calculations in which it divides the chromaticity into component wavelength bands, each band two nanometers (nm) wide, and performs iterative calculations. The first xe2x80x9cNormalizexe2x80x9d iterative routine forces convergence between the initial weighted chromaticity and the measured chromaticity. The second xe2x80x9cCalculate Adjustmentxe2x80x9d iterative routine forces convergence between the measured chromaticity and the target chromaticity. The resulting output is the mass in grams of each phosphor to be added to the mix of phosphors to obtain the desired chromaticity from the product or lamp.